Fe-deficiency response in Parietaria diffusa : a calcicole plant

Pellitory of the wall (Parietaria diffusa L.), a dicotyledonous wild plant belonging to the family of Urticaceae, is widespread on calcareous soils, and also on walls and debris, were lime concentration, sometimes, is extremely high; it may then be considered a calcicole plant. Since high pH values and the presence of CaCO3 and HCO3- cause low Fe solubility, its availability in such substrates could be the ecological factor limiting the distribution of spontaneous plants in calcareous soils, and a calcareous soil-born plant should be characterized by a higher Fe-efficiency in comparison with calcifuge ones. Parietaria diffusa was grown in nutrient solutions in the presence and in the absence of Fe, and in the presence of CaCO3 and bicarbonate at two concentrations (5 and 15mM), in order to simulate a natural substrate with different lime contents. Some biochemical parameters were determined and the morphological and hystological modifications of the root system were evaluated in order to verify whether Parietaria is a Fe-efficient plant and adopts the adaptive mechanisms of Strategy I Fe-efficient plants

Physiological and biochemical responses for two cultivars of Pisum sativum (''Merveille de Kelvedon'' and ''Lincoln'') to iron deficiency conditions

The aim of this work was to compare the tolerance and the physiological responses to Fe deficiency of two Pisum sativum cultivars ("Merveille de kelvedon" and "Lincoln") commonly cultivated in Tunisia. We studied the effects of Fe deficiency on: (i) chlorophyll content, relative growth rate (RGR) and Fe status, (ii) rhizosphere acidification, (iii) changes under Fe-deficient conditions in the activities of two root enzymes, the first related to the proton extrusion (H+-ATPase) and the second to iron reduction mechanism (Fe(III)-chelate-reductase: FCR). Three treatments were used: C, control, complete nutrient solution (CNS) containing 30 \u3bcM Fe; DD, direct deficiency, CNS without iron; ID, indirect deficiency, CNS containing 30 \u3bcM Fe + lime. Fe deficiency led to a significant decrease of chlorophyll content in both cultivars. The below reduction was observed in Fe-deficient plants of Merveille de Kelvedon. In addition, relative growth of shoots and whole plant was not affected by Fe deficiency. H+-ATPase and FCR activities were more stimulated in Merveille de Kelvedon than in Lincoln, under DD and ID Fe deficiency. The capacity of this cultivar to maintain plant growth and to preserve adequate chlorophyll synthesis under iron-limiting conditions is related to its better Fe-use efficiency, in addition to its high acidification and root reducing capacities. This allows us to suggest that Merveille de Kelvedon is more effective in overcoming Fe deficiency than Lincoln